Cysticercosis is a systemic illness caused by dissemination of the larval form of the pork tapeworm, Taenia solium. Encystment of larvae can occur in almost any tissue. Involvement of the central nervous system (CNS), known as neurocysticercosis (NCC), is the most clinically important manifestation of the disease and may present with dramatic findings. Incidence of cysticercosis is increasing within developed countries.

Quote:

Pathophysiology
Humans are the definitive T solium hosts and can carry an intestinal adult tapeworm (taeniasis), often without symptoms. Intermittent fecal shedding of egg-containing proglottids or free T solium eggs ensues, with the intention that the intermediate host (normally pigs) will ingest the excreted eggs in contaminated food or water. T solium embryos penetrate the GI mucosa of the pig and are hematogenously disseminated to peripheral tissues with resultant formation of larval cysts (cysticerci). When undercooked pork is consumed, an intestinal tapeworm will again be formed, completing the life cycle of the worm.

Human cysticercosis occurs when T solium eggs are ingested via fecal-oral transmission from a tapeworm host. The human then becomes an accidental intermediate host, with development of cysticerci within organs. Cysticerci may be found in almost any tissue. The most frequently reported locations are skin, skeletal muscle, heart, eye, and most importantly, the CNS (NCC).
Symptomatology of NCC is largely dependent on the presence of pericystic inflammation, the absence of which will usually manifest as asymptomatic disease.

Host inflammatory response to cysticerci depends on the parasite's ability to evade host immunity; therefore, inflammation is restricted to currently degenerating cysts whose ability to evade host defenses is faltering. Lack of inflammation occurs with both healthy cysticerci and those that have involuted, termed active and inactive disease, respectively. Upon involution, cysts undergo granulomatous change and exhibit calcification. Cysts in various stages of viability can be seen simultaneously in one host.

In patients with advanced HIV disease and compromised cell-mediated immunity, NCC may is exist without significant host response and is likely to be asymptomatic. For this reason, in symptomatic patients with CD4 counts under 200 cells/mm3 alternative diagnoses should be considered more likely.
Clinical manifestations of NCC depend primarily on the number and location of CNS cysticerci and the host's immune response to infection. Serious pathologic findings of NCC can include seizures, obstructive hydrocephalus, meningoencephalitis, and vascular accidents.

Involvement of brain parenchyma is common and leads to the most frequent presentation of seizure or headache. Extraparenchymal ventricular and subarachnoid cysts also are found. These carry a worse prognosis and often lead to obstructing hydrocephalus requiring surgical intervention. Cysticerci within the basilar cisterns or Sylvian fissures may become quite large. Those within the cisterns may also cause serious vasculitis and stroke. Spinal NCC is rare.

Quote:

Where is cysticercosis found?
The tapeworm that causes cysticercosis is found worldwide. Infection is found most often in rural, developing countries with poor hygiene where pigs are allowed to roam freely and eat human feces. This allows the tapeworm infection to be completed and the cycle to continue. Infection can occur, though rarely, if you have never traveled outside of the United States. Taeniasis and cysticercosis are very rare in Muslim countries where eating pork is forbidden.

Quote:

How can I get cysticercosis?
By accidentally swallowing pork tapeworm eggs. Tapeworm eggs are passed in the bowel movement of a person who is infected. These tapeworm eggs are spread through food, water, or surfaces contaminated with feces. This can happen by drinking contaminated water or food, or by putting contaminated fingers to your mouth. A person who has a tapeworm infection can reinfect themselves (autoinfection). Once inside the stomach, the tapeworm egg hatches, penetrates the intestine, travels through the bloodstream and may develop into cysticerci in the muscles, brain, or eyes.

Quote:

What are the signs and symptoms of cysticercosis?
Signs and symptoms will depend on the location and number of cysticerci in your body.

Quote:

Cysticerci in the muscles:
Cysticerci in the muscles generally do not cause symptoms. However, you may be able to feel lumps under your skin.

Quote:

Cysticerci in the eyes:
Although rare, cysticerci may float in the eye and cause blurry or disturbed vision. Infection in the eyes may cause swelling or detachment of the retina.

Quote:

Neurocysticercosis (cysticerci in the brain, spinal cord):
Symptoms of neurocysticercosis depend upon where and how many cysticerci (often called lesions) are found in the brain. Seizures, and headaches are the most common symptoms. However, confusion, lack of attention to people and surroundings, difficulty with balance, swelling of the brain (called hydrocephalus) may also occur. Death can occur suddenly with heavy infections.